Local area networks consisting of a number of personal computers, utilize electronic means, including wire connections to transmit information from one station to another. While transmission of data through optical fibers is preferable to electronic transmissions, optical communication systems (OCS) are presently too costly to Justify their use in local area networks. The cost is prohibitive because the lasers and the modulation hardware used in these systems is expensive.
The transmission of data through fiber-optic cables is preferable because they can transmit signals with a bandwidth of several gigahertz over distances of several of tens or hundreds of kilometers (depending on the power of the signal) with losses of fractional decibels per kilometer. Compared with coaxial cables, which are dispersive (different frequencies travel at different speeds, and with different amounts of loss, thereby corrupting waveforms), fiber-optic cables can be designed so that dispersion is negligible. Also, unlike ordinary cables, they do not act as antennas for radio interference or impulsive noise. They are lighter, safer, and more rugged than conventional cables, and they are potentially less expensive.
Prior transmitters used in OCSs, have not included the self-pulsating laser diodes (SPLD) because it does not generate a signal of sufficient power for use in long-distance OCSs. Moreover, the SPLD generates both an optical frequency and a self-pulsating sub-carrier frequency, the latter of which has been considered detrimental to SPLD's performance. Many researchers have concentrated their efforts on removing, or working around the self-pulsating frequency. The lasers used in prior art OCSs do not generate the self-pulsation.